Double-subcripted array

I need to label the elements of 3-by-5 double-subscripted array [sales] to indicate the order in which they are set to zero by the following program segment and I don't have the first clue:


for ( row = 0; row < 3; row++ )
for ( column = 0; column < 5; column++ )
sales[ row ] [ column ] = 0;

What do you mean by labelling? Handwritting how the for loop assigns 0 to the array?

If so read this tutorial

Then this one.